Adhesion between polymer substrates and autocatalytic plates

ABSTRACT

Provided is a method and apparatus for improving adhesion between a polymer article and a metal plate. The method includes providing a polymer article, and hydrolyzing a surface of the polymer article using an acidic solution to obtain carboxylic acid groups at the surface. The method also includes grafting polyphenols to the carboxylic acid groups by esterification that is catalyzed by the acidic solution, and chelating metal ions to the grafted polyphenols to form polyphenol-metal complexes. The apparatus includes a body formed by additive manufacturing, and a metal plating formed on a surface of the body by electroless metal plating after a surface preparation process. The surface preparation process includes treating the surface with an acidic solution to obtain carboxylic acid groups at the surface, treating the surface with a polyphenol solution to obtain polyphenols grafted to the carboxylic acid groups, and chelating metal ions to the polyphenols.

FIELD

This disclosure relates generally to additive manufacturing, and moreparticularly to metallic plating of polymer substrates formed byadditive manufacturing.

BACKGROUND

Additive manufacturing is utilized to fabricate 3-dimensional (3D) partsor products by adding layer-upon-layer of material. Additivemanufacturing systems utilize 3D-modeling (i.e., CAD) software,computer-controlled additive-manufacturing equipment, and raw materials(feed stocks) in powder, wire, or liquid form. A variety of rawmaterials may be used in additive manufacturing to create products.Examples of such materials include plastics, metals, concrete, andglass. Some raw materials have material property limitations which limitpotential applications. One way to improve on these limitations is toadd a plating which can improve stiffness, chemical/corrosionresistance, and flammability characteristics. Unfortunately, some basematerials do not allow for proper adhesion of the plating material.

SUMMARY

The subject matter of the present application has been developed inresponse to the present state of the art, and in particular, in responseto the shortcomings of metal-plating methods of polymer articles, thathave not yet been fully solved by currently available techniques.Accordingly, the subject matter of the present application has beendeveloped to provide a method and apparatus that overcome at least someof the above-discussed shortcomings of prior art techniques.

The following is a non-exhaustive list of examples, which may or may notbe claimed, of the subject matter, disclosed herein.

Disclosed herein is a method includes providing a polymer article, andhydrolyzing a surface of the polymer article using an acidic solution toobtain carboxylic acid groups at the surface. The method also includesgrafting polyphenols to the carboxylic acid groups by esterificationthat is catalyzed by the acidic solution, and chelating metal ions tothe grafted polyphenols to form polyphenol-metal complexes. Thepreceding subject matter of this paragraph characterizes example 1 ofthe present disclosure.

The polymer article is formed by additive manufacturing. The precedingsubject matter of this paragraph characterizes example 2 of the presentdisclosure, wherein example 2 also includes the subject matter accordingto example 1 above.

The polymer article is made of a synthetic polyamide. The precedingsubject matter of this paragraph characterizes example 3 of the presentdisclosure, wherein example 3 also includes the subject matter accordingto example 2 above.

Examples of a synthetic polyamide suitable for use in the presentdisclosure include, but are not limited to, polyamide 11, and polyamide12. The preceding subject matter of this paragraph characterizes example4 of the present disclosure, wherein example 4 also includes the subjectmatter according to example 3 above.

The polyphenol is tannic acid. The preceding subject matter of thisparagraph characterizes example 5 of the present disclosure, whereinexample 5 includes the subject matter according to example 1 above.

The method of chelating metal ions includes treating the surface with ametal salt solution. The preceding subject matter of this paragraphcharacterizes example 6 of the present disclosure, wherein example 6includes the subject matter according to example 1 above.

The metal salt solution has a metal selected from the group consistingof Fe, Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au. The preceding subjectmatter of this paragraph characterizes example 7 of the presentdisclosure, wherein example 7 includes the subject matter according toexample 6 above.

Additionally disclosed herein is a body formed by additivemanufacturing, and a metal plating formed on a surface of the body byelectroless metal plating subsequent to a surface preparation process.The surface preparation process includes, in certain examples, treatingthe surface with an acidic solution to obtain carboxylic acid groups atthe surface, treating the surface with a polyphenol solution to obtainpolyphenols grafted to the carboxylic acid groups, and chelating metalions to the polyphenols. The preceding subject matter of this paragraphcharacterizes example 8 of the present disclosure.

The body is made of a synthetic polyamide. The preceding subject matterof this paragraph characterizes example 9 of the present disclosure,wherein example 9 includes the subject matter according to example 8above.

Examples of suitable polyamides include polyamide 11, and polyamide 12.The preceding subject matter of this paragraph characterizes example 10of the present disclosure, wherein example 10 includes the subjectmatter according to example 9 above.

The polyphenol is tannic acid. The preceding subject matter of thisparagraph characterizes example 11 of the present disclosure, whereinexample 11 includes the subject matter according to example 8 above.

The surface preparation process also includes treating the surface witha metal salt solution. The preceding subject matter of this paragraphcharacterizes example 12 of the present disclosure, wherein example 12includes the subject matter according to example 8 above.

The metal salt solution has a metal selected from the Fe, Ni, Ru, Rh,Pd, Ag, Os, Ir, Pt, and Au. The preceding subject matter of thisparagraph characterizes example 13 of the present disclosure, whereinexample 13 also includes the subject matter according to example 12above.

Additionally disclosed herein is a method of metal plating a polymerarticle. The method includes treating a polymer article with an acidicsolution to hydrolyze a surface of the polymer article and obtaincarboxylic acid groups at the surface, treating the polymer article witha polyphenol solution to graft polyphenol molecules to the carboxylicacid groups, treating the polymer article with a metal salt solution toform polyphenol-metal complexes, and treating the polymer article withan electroless metal plating bath to metal plate the surface. Thepreceding subject matter of this paragraph characterizes example 14 ofthe present disclosure.

The polymer article is formed by additive manufacturing. The precedingsubject matter of this paragraph characterizes example 15 of the presentdisclosure, wherein example 15 also includes the subject matteraccording to example 14 above.

The polymer article is made of a synthetic polyamide. The precedingsubject matter of this paragraph characterizes example 16 of the presentdisclosure, wherein example 16 also includes the subject matteraccording to example 15 above.

The synthetic polyamide may be either polyamide 11 or polyamide 12. Thepreceding subject matter of this paragraph characterizes example 17 ofthe present disclosure, wherein example 17 also includes the subjectmatter according to example 16 above.

The polyphenol solution is tannic acid. The preceding subject matter ofthis paragraph characterizes example 18 of the present disclosure,wherein example 18 also includes the subject matter according to example14 above.

Treating the polymer article with the metal salt solution includeschelating metal ions to the grafted polyphenol molecules. The precedingsubject matter of this paragraph characterizes example 19 of the presentdisclosure, wherein example 19 also includes the subject matteraccording to example 14 above.

The metal salt solution has a metal selected from Fe, Ni, Ru, Rh, Pd,Ag, Os, Ir, Pt, and Au. The preceding subject matter of this paragraphcharacterizes example 20 of the present disclosure, wherein example 20also includes the subject matter according to example 19 above.

The described features, structures, advantages, and/or characteristicsof the subject matter of the present disclosure may be combined in anysuitable manner in one or more examples and/or implementations. In thefollowing description, numerous specific details are provided to imparta thorough understanding of examples of the subject matter of thepresent disclosure. One skilled in the relevant art will recognize thatthe subject matter of the present disclosure may be practiced withoutone or more of the specific features, details, components, materials,and/or methods of a particular example or implementation. In otherinstances, additional features and advantages may be recognized incertain examples and/or implementations that may not be present in allexamples or implementations. Further, in some instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the subject matter of the presentdisclosure. The features and advantages of the subject matter of thepresent disclosure will become more fully apparent from the followingdescription and appended claims, or may be learned by the practice ofthe subject matter as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the subject matter may be more readilyunderstood, a more particular description of the subject matter brieflydescribed above will be rendered by reference to specific examples thatare illustrated in the appended drawings. Understanding that thesedrawings depict only typical examples of the subject matter and are nottherefore to be considered to be limiting of its scope, the subjectmatter will be described and explained with additional specificity anddetail through the use of the drawings, in which:

FIGS. 1a-1d are schematic diagrams illustrating different stages of aprocess for surface preparation of a polymer article that improves theadhesion of an electroless plating to a polymer article, in accordancewith some examples of the present disclosure;

FIG. 2 is a schematic diagram illustrating one example of a polyphenolcoordination complex in accordance with the present disclosure; and

FIG. 3 is a method of preparing a polyamide article surface for improvedadhesion in accordance with examples of the present disclosure.

DETAILED DESCRIPTION

Reference throughout this specification to “one example,” “an example,”or similar language means that a particular feature, structure, orcharacteristic described in connection with the example is included inat least one example of the present disclosure. Appearances of thephrases “in one example,” “in an example,” and similar languagethroughout this specification may, but do not necessarily, all refer tothe same example. Similarly, the use of the term “implementation” meansan implementation having a particular feature, structure, orcharacteristic described in connection with one or more examples of thepresent disclosure, however, absent an express correlation to indicateotherwise, an implementation may be associated with one or moreexamples. Like reference numbers signify like elements throughout thedescription of the figures.

The method and apparatus of this disclosure provide an improvement tothe adhesion between a polymer substrate and a metal plate. The methodsdescribed below are applicable to devices or apparatuses that are usedin the manufacturing, assembly, or repair of an aircraft. However, theprinciples of the present disclosure may be applied to other industries,such as the automotive industry or other industries.

The methods embodied herein may be employed during any one of the stepsof manufacturing, assembly, or repair of the aircraft. For example,components or subassemblies may be fabricated or manufactured for use inpropulsion systems, electrical systems, hydraulic systems, environmentalsystems, etc. The methods described here may be utilized during theproduction of the aircraft to expedite assembly or reduce the cost ofthe aircraft through the use of additive manufacturing. Additivemanufacturing is useful to create a wide variety of products havingdifferent shapes and sizes by forming the product layer-by-layer.Beneficially, the methods disclosed here improve stiffness, chemicalcorrosion resistance, and flammability characteristics ofcomponents/articles formed by additive manufacturing. These benefits andfeatures will be described in greater detail below.

FIGS. 1a-1d are schematic diagrams illustrating different stages of aprocess for surface preparation of a polymer article that improves theadhesion of an electroless plating to a polymer article, in accordancewith some examples of the present disclosure. Depicted in FIGS. 1a-1d isa portion of a cross-section of a polymer article (“article”) 100(formed by additive manufacturing) at different stages of the metalplating/coating process. The microscopic cross-section depicted is forillustrative purposes only to aid in the discussion of the process forimproving adhesion between the article 100 and the metal plating 110.The surface 104 of the article 100, although depicted as jagged, whenviewed by the naked eye may appear smooth.

The surface 104 of the article 100, formed by additive manufacturing,may have a rough surface finish, e.g., on the order of about 600-1000microinches R_(a). Such rough surfaces may have undesirable effects andlimit applications of the article 100 in certain environments. Coatingthe article 100 with a metal to, in effect, mask the rough surfacefinish of the surface 104 helps to improve the effectiveness of andincrease the applicability of the article 100.

In some examples, as shown in FIG. 1a , the article 100 is formed by oneor more of the following additive manufacturing techniques, including,but not limited to, vat photopolymerization, material jetting, binderjetting, material extrusion, powder bed fusion, sheet lamination, ordirected energy deposition. The methods of additive manufacturingdescribed for the formation of the article 100 are not intended to belimiting, but are provided to demonstrate that many alternatives arepossible, with all of the alternative intended to be within the scope ofthe present disclosure.

In certain examples, the article 100 is made of a polyamide. Suitablepolyamides include condensation polymers formed of amines and carboxylicacids, and/or one or more aminocarboxylic acids. Polyamides include, butare not limited to, aliphatic, aromatic, and/or semi-aromaticpolyamides. The polyamides may be homopolymer, copolymer, or higherorder polymers. Additionally, the article 100 may be made of two or moredifferent polyamides. In particular, the article 100 may be made ofpolyamide 11 (PA11) or polyamide 12 (PA12) polymers. PA11 is produced bythe polymerization of 11-aminoundecanoic acid. The repeating unit ofPA11 may be represented as HN—(CH₂)₁₀—CO, where (CH₂)₁₀ is the repeatingunit R of the polymer chain. Similarly, PA12 may be represented asHN—(CH₂)₁₁—CO. It is contemplated that other polyamides may be suitablefor use with the methods of the present disclosure. Examples of otherpolyamides include, but are not limited to, aliphatic polyamides such aspolyamide 6; polyamide 6,6; polyamide 4,6; polyamide 6,9; polyamide6,10; polyamide 6,12; polyamide 9,10; polyamide 9,12; polyamide 9,13;polyamide 9,14; polyamide 9,15; polyamide 6,16; etc.; semi-aromaticpolyamides; polyterethalamides; and copolymers and mixtures of thesepolyamides.

Because the article 100 is made of a polymer (e.g., polyamides such asPA11 or PA12), traditional metal coating methods, that rely on hightemperatures or electrical conductivity often fail. Beneficially, themethods and processes of the present disclosure enable the grafting ofmetal ions to the surface via a grafting mechanism that forms chemicalbonds of a metal ion catalyst to the surface of the article 100 using apolyphenol solution. The metal ions present a suitable surface for metalcoating.

Briefly stated, the method for improving adhesion between the article100, which can be made of a polymer polyamide via additive manufacturingtechniques as disclosed above, by metal coating the article 100 includesthe steps of: (1) hydrolyzing the surface 104 the article 100 using adilute acidic solution to create carboxylic acid groups on the surface104; (2) treating the surface 104 with a polyphenol solution to graftpolyphenol molecules to the carboxylic acid groups; (3) treating thesurface 104 with a metal salt solution to form polyphenol-metalcomplexes; and (4) treating the surface 104 with an electroless metalplating bath to metal plate the surface. Each of these steps isdescribed in greater detail below.

Regarding step (1), hydrolyzing the surface 104 of the article 100includes treating the surface 104 with a dilute acidic solution. Theacidic solution may be acetic acid (CH₃COOH) in the form of a liquidmixture. The acetic acid solution may have a pH in the range of betweenabout 2.4 and 3.4, depending on the concentration of the acetic acid inan aqueous solution. In some examples, the concentration may be in therange of between about 0.01 M and 1.0 M. Buffers may be used including,but not limited to, bicarbonate, bisulphate, etc. The treatment of thesurface with the acidic solution may be carried out at ambienttemperatures, or alternatively at temperatures up to 75° C. Optionally,the treatment may be carried out in other inert gas environments such asnitrogen, argon, etc. The treatment of the dilute acidic solution may beapplied for a time in the range of between about 15 and 30 minutes. Theacetic acid solution hydrolyzes the surface of the article 100 to formcarboxylic acid groups (COOH consisting of a carbonyl group and ahydroxyl group) on the surface 104 of the article 100.

Surface carboxylic acid groups form intermolecular hydrogen bonds withpolyphenols, which is advantageous for anchoring polyphenol-metalcomplexes 106 (see FIG. 1b ). Following the treatment of the articlewith the acidic solution, the article 100 is treated with a polyphenolsolution without rinsing the article 100. Acidic solution still presenton the surface 104 of the article 100 catalyzes esterification tochemically bond alcohol groups of the polyphenol to carbonyl groups ofthe carboxylic acid groups. In certain examples, the polyphenol istannic acid in an aqueous solution having a concentration in the rangeof between about 0.01 M and 10.0 M. The surface 104 may be treated inambient conditions (e.g., ambient temperatures and pressures) for adwell time in the range of between about 2 and 30 minutes.Alternatively, the temperature may be raised to above ambienttemperatures, such as up to 75° C., and performed in an inert gasenvironment.

Following the treatment of the surface 104 with the polyphenol solution,the surface 104 of the article 100 is treated with a metal-salt solutionto introduce metallic ions and chelate the metal ions with thepolyphenol to form polyphenol-metal complexes 106, as depicted in FIG.1b . Suitable metal-salt solutions include, but are not limited to,FeCL₂, NiCL₂, or other noble metal salts (i.e., salts formed from Fe,Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au). The metal-salt solution may beapplied for a period of time in the range of between about 10 minutesand 3 hours. Buffered saline solutions may optionally be added tomaintain a pH in the range of between about 6.8 and 7.4. Following themetal-salt solution treatment, the article may be rinsed with water inpreparation for metal plating.

FIGS. 1c and 1d depict metal plating steps of the article 100. Metalmolecules that form the metal plating 110 may now be deposited andadhered to the polyphenol-metal complexes 106. Metal coating or platingrefers to processes such as electroless plating, electroplating,spraying, vapor deposition, immersion processes, solution dippingprocesses, and powder coating. Metals suitable for use include, but arenot limited to, nickel, iron, copper, silver, cobalt, zinc, titanium,platinum, aluminum, palladium, lead, tin, etc., or any combination toform a metal alloy. In certain examples, improved metal-plating adhesionis achieved with electroless plating.

A thin layer of metal may be initially deposited (see FIG. 1c ) by achemical (electroless) deposition. FIG. 1c depicts how the metal ions108 of the initial deposition may be deposited around the metal ions 109of the polyphenol-metal complexes 106. Copper or nickel is used as theinitial metal layer, in certain examples, however, in other examples,other metals are used. Further electroless deposition may be used, oralternatively, other types of electrolytic deposition may be used toincrease the thickness of the metal layer (see FIG. 1d ). The metallayer can be a single metal, or a metal alloy, and deposited to athickness in the range of between about 1 and 50 microns.

FIG. 2 is a schematic diagram illustrating one example of apolyphenol-metal complex 106 in accordance with the present disclosure.The polyphenol-metal complex 106 is formed of polyphenol molecules 200bonded to a central metal ion 202. Two or more separate coordinate bonds204 couple the metal ion 202 to multiple-bonded polyphenol molecules 200(i.e., ligands). As described above, the polyphenol-metal complex 106couples to carboxylic acid groups, bonded to the surface of a polymerarticle, via esterification.

FIG. 3 illustrates a method 300 of preparing a surface of a polymerarticle, such as the surface 104 of the article 100, for improvedadhesion in accordance with examples of the present disclosure. Themethod 300 includes forming an article 100 by additive manufacturing atstep 302. At step 304, the method 300 includes hydrolyzing the surfaceof the article 100 by treating the surface 104 with a dilute acidicsolution to form carboxylic acid groups.

At step 306 of the method 300, the surface of the article is treatedwith a polyphenol solution. Acid left over from step 304 catalyzesesterification of the polyphenol solution with the carboxyl groups tobond polyphenol molecules to the surface of the article. At step 308 ofthe method 300, a catalyst metal salt solution is added to thepolyphenol solution to chelate metal ions to the polyphenol molecules.At step 310 of the method 300, the article is removed from the solutionand washed, which places the polymer article in condition for plating.At step 312 of the method 300, the article is plated by treating thepolymer article with an electroless metal plating bath. Alternativemethods of plating may be used as described above.

In the above description, certain terms may be used such as “up,”“down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,”“over,” “under” and the like. These terms are used, where applicable, toprovide some clarity of description when dealing with relativerelationships. But, these terms are not intended to imply absoluterelationships, positions, and/or orientations. For example, with respectto an object, an “upper” surface can become a “lower” surface simply byturning the object over. Nevertheless, it is still the same object.Further, the terms “including,” “comprising,” “having,” and variationsthereof mean “including but not limited to” unless expressly specifiedotherwise. An enumerated listing of items does not imply that any or allof the items are mutually exclusive and/or mutually inclusive, unlessexpressly specified otherwise. The terms “a,” “an,” and “the” also referto “one or more” unless expressly specified otherwise. Further, the term“plurality” can be defined as “at least two.” Moreover, unless otherwisenoted, as defined herein a plurality of particular features does notnecessarily mean every particular feature of an entire set or class ofthe particular features.

Additionally, instances in this specification where one element is“coupled” to another element can include direct and indirect coupling.Direct coupling can be defined as one element coupled to and in somecontact with another element. Indirect coupling can be defined ascoupling between two elements not in direct contact with each other, buthaving one or more additional elements between the coupled elements.Further, as used herein, securing one element to another element caninclude direct securing and indirect securing. Additionally, as usedherein, “adjacent” does not necessarily denote contact. For example, oneelement can be adjacent another element without being in contact withthat element.

As used herein, the phrase “at least one of”, when used with a list ofitems, means different combinations of one or more of the listed itemsmay be used and only one of the items in the list may be needed. Theitem may be a particular object, thing, or category. In other words, “atleast one of” means any combination of items or number of items may beused from the list, but not all of the items in the list may berequired. For example, “at least one of item A, item B, and item C” maymean item A; item A and item B; item B; item A, item B, and item C; oritem B and item C. In some cases, “at least one of item A, item B, anditem C” may mean, for example, without limitation, two of item A, one ofitem B, and ten of item C; four of item B and seven of item C; or someother suitable combination.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to, e.g., a “second” item does notrequire or preclude the existence of, e.g., a “first” or lower-numbereditem, and/or, e.g., a “third” or higher-numbered item.

As used herein, a system, apparatus, structure, article, element,component, or hardware “configured to” perform a specified function isindeed capable of performing the specified function without anyalteration, rather than merely having potential to perform the specifiedfunction after further modification. In other words, the system,apparatus, structure, article, element, component, or hardware“configured to” perform a specified function is specifically selected,created, implemented, utilized, programmed, and/or designed for thepurpose of performing the specified function. As used herein,“configured to” denotes existing characteristics of a system, apparatus,structure, article, element, component, or hardware which enable thesystem, apparatus, structure, article, element, component, or hardwareto perform the specified function without further modification. Forpurposes of this disclosure, a system, apparatus, structure, article,element, component, or hardware described as being “configured to”perform a particular function may additionally or alternatively bedescribed as being “adapted to” and/or as being “operative to” performthat function.

The schematic flow chart diagrams included herein are generally setforth as logical flow chart diagrams. As such, the depicted order andlabeled steps are indicative of one example of the presented method.Other steps and methods may be conceived that are equivalent infunction, logic, or effect to one or more steps, or portions thereof, ofthe illustrated method. Additionally, the format and symbols employedare provided to explain the logical steps of the method and areunderstood not to limit the scope of the method. Although various arrowtypes and line types may be employed in the flow chart diagrams, theyare understood not to limit the scope of the corresponding method.Indeed, some arrows or other connectors may be used to indicate only thelogical flow of the method. For instance, an arrow may indicate awaiting or monitoring period of unspecified duration between enumeratedsteps of the depicted method. Additionally, the order in which aparticular method occurs may or may not strictly adhere to the order ofthe corresponding steps shown.

The present subject matter may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed examples are to be considered in all respects only asillustrative and not restrictive. All changes which come within themeaning and range of equivalency of the claims are to be embraced withintheir scope.

What is claimed is:
 1. A method of preparing a polymer surface forelectroless metal plating, the method comprising: providing a polymerarticle; hydrolyzing a surface of the polymer article using an acidicsolution to obtain carboxylic acid groups at the surface; graftingpolyphenols to the carboxylic acid groups by esterification that iscatalyzed by the acidic solution; and chelating metal ions to thegrafted polyphenols to form polyphenol-metal complexes.
 2. The method ofclaim 1, further comprising forming the polymer article by additivemanufacturing.
 3. The method of claim 2, wherein the polymer article ismade of a synthetic polyamide.
 4. The method of claim 3, wherein thesynthetic polyamide is selected from the group consisting of polyamide11 and polyamide
 12. 5. The method of claim 1, wherein the polyphenolcomprises tannic acid.
 6. The method of claim 1, wherein chelating metalions to the grafted polyphenols further comprises treating the surfacewith a metal salt solution.
 7. The method of claim 6, where the metalsalt solution comprises a solution having a metal selected from thegroup consisting of Fe, Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au.
 8. Ametal-coated polymer device comprising: a body formed by additivemanufacturing; and a metal plating formed on a surface of the body byelectroless metal plating subsequent to a surface preparation process,where the surface preparation process comprises: treating the surfacewith an acidic solution to obtain carboxylic acid groups at the surface;treating the surface with a polyphenol solution to obtain polyphenolsgrafted to the carboxylic acid groups; and chelating metal ions to thepolyphenols.
 9. The metal-coated polymer device of claim 8, where thebody is made of a synthetic polyamide.
 10. The metal-coated polymerdevice of claim 9, where the synthetic polyamide is selected from thegroup consisting of polyamide 11, and polyamide
 12. 11. The metal-coatedpolymer device of claim 8, where the polyphenol comprises tannic acid.12. The metal-coated polymer of claim 8, where chelating metal ions tothe polyphenols further comprises treating the surface with a metal saltsolution.
 13. The metal-coated polymer of claim 12, where the metal saltsolution comprises a solution having a metal selected from the groupconsisting of Fe, Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au.
 14. A methodof metal plating a polymer article, the method comprising: treating apolymer article with an acidic solution to hydrolyze a surface of thepolymer article and obtain carboxylic acid groups at the surface;treating the polymer article with a polyphenol solution to graftpolyphenol molecules to the carboxylic acid groups; treating the polymerarticle with a metal salt solution to form polyphenol-metal complexes;and treating the polymer article with an electroless metal plating bathto metal plate the surface.
 15. The method of claim 14, where thepolymer article is formed by additive manufacturing.
 16. The method ofclaim 15, where the polymer article is made of a synthetic polyamide.17. The method of claim 16, where the synthetic polyamide is selectedfrom the group consisting of polyamide 11, and polyamide
 12. 18. Themethod of claim 14, where the polyphenol solution comprises tannic acid.19. The method of claim 14, where treating the polymer article with themetal salt solution comprises chelating metal ions to the graftedpolyphenol molecules.
 20. The method of claim 19, where the metal saltsolution comprises a solution having a metal selected from the groupconsisting of Fe, Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au.